Java compiler – path – version – java home

from here

First run /usr/libexec/java_home -V which will output something like the following:
Matching Java Virtual Machines (3): 1.8.0_05, x86_64: "Java SE 8" /Library/Java/JavaVirtualMachines/jdk1.8.0_05.jdk/Contents/Home 1.6.0_65-b14-462, x86_64: "Java SE 6" /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home 1.6.0_65-b14-462, i386: "Java SE 6" /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home /Library/Java/JavaVirtualMachines/jdk1.8.0_05.jdk/Contents/Home 

Pick the version you want to be the default (1.6.0_65-b14-462 for arguments sake) then:

export JAVA_HOME=`/usr/libexec/java_home -v 1.6.0_65-b14-462`

or you can specify just the major version, like:

export JAVA_HOME=`/usr/libexec/java_home -v 1.8`

Now when you run java -version you will see:

java version "1.6.0_65"
Java(TM) SE Runtime Environment (build 1.6.0_65-b14-462-11M4609)
Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-462, mixed mode)

Add the export JAVA_HOME… line to your shell’s init file.

For Bash (as stated by antonyh):

export JAVA_HOME=$(/usr/libexec/java_home -v 1.8)

For Fish (as stated by ormurin)

set -x JAVA_HOME (/usr/libexec/java_home -d64 -v1.8)

Updating the .zshrc file should work:

nano ~/.zshrc

export JAVA_HOME=$(/usr/libexec/java_home -v 1.8.0)



Understanding /etc/shadow file fields and format

Basically, the /etc/shadow file stores secure user account information. All fields are separated by a colon (:) symbol. It contains one entry per line for each user listed in /etc/passwd file. Generally, shadow file entry looks as follows (click to enlarge image):

/etc/shadow file format

/etc/shadow file format (click to enlarge)

As with the /etc/passwd, each field in the shadow file is also separated with “:” colon characters as follows:


  1. Username : A valid account name, which exist on the system.
  2. Password : Your encrypted password is in hash format. The password should be minimum 15-20 characters long including special characters, digits, lower case alphabetic and more. Usually password format is set to $id$salt$hashed, The $id is the algorithm prefix used On GNU/Linux as follows
    1. $1$ is MD5
    2. $2a$ is Blowfish
    3. $2y$ is Blowfish
    4. $5$ is SHA-256
    5. $6$ is SHA-512
    6. $y$ is yescrypt
  3. Last password change (lastchanged) : The date of the last password change, expressed as the number of days since Jan 1, 1970 (Unix time). The value 0 has a special meaning, which is that the user should change her password the next time she will log in the system. An empty field means that password aging features are disabled.
  4. Minimum : The minimum number of days required between password changes i.e. the number of days left before the user is allowed to change her password again. An empty field and value 0 mean that there are no minimum password age.
  5. Maximum : The maximum number of days the password is valid, after that user is forced to change her password again.
  6. Warn : The number of days before password is to expire that user is warned that his/her password must be changed
  7. Inactive : The number of days after password expires that account is disabled.
  8. Expire : The date of expiration of the account, expressed as the number of days since Jan 1, 1970.

Linux Administrator Tips

Find all file with permission to run if belong to wheel or sudo group. Bit suid active

find / -perm /u+s 2>/dev/null

The denied access is not visualized with 2>/del/null

Command to show who has access to a file or folder : lsof <file/folder name>

Is possible to use the command  fuser <file name>


sudo visudo manage the user permission

id user for check the groups

ulimit -a check the limit and set it for single user

to set the limit in global level user : /etc/security/limits.conf

RoundCube configuration folder

Permission list for the roundcube folder :

drwxrwxr– 11 apache apache 4096 Jun 8 14:19 enigma_pgp_homedir

drwxrwxr– 2 apache apache 4096 Jul 12 16:34 logs


Top 20 Open Source Cyber Security Monitoring Tools in 2023

From here

As cyber threats continue to evolve, security professionals require reliable tools to defend against security vulnerabilities, protect sensitive data, and maintain network security. Open source cyber security tools provide a cost-effective solution for individuals and organizations to combat these threats on-premises and with cloud security and mobile devices. Let’s consider the top 25 open-source cyber security monitoring tools in 2023 that help ensure continuous network and system performance monitoring.

Table of contents

What are the Top Cybersecurity Threats Today?

As cyber threats continue to evolve and become more sophisticated, organizations must stay informed and prepared to defend against a wide range of security risks.

Here are the top cybersecurity threats that businesses and individuals should be aware of today:

1. Phishing Attacks: Phishing attacks are a prevalent form of social engineering where cybercriminals use deceptive emails or websites to trick users into revealing sensitive information or installing malware. These attacks often target login credentials, financial information, and other personal data.

2. Ransomware: Ransomware is a type of malicious software that encrypts a victim’s files or locks their systems, demanding a ransom payment to restore access. Ransomware attacks can cause significant financial losses and operational disruptions for organizations.

3. Insider Threats: Insider threats refer to security risks posed by employees, contractors, or other individuals with authorized access to an organization’s systems and data. These threats can result from malicious intent or negligence, leading to data breaches or system compromises.

4. Supply Chain Attacks: Also known as third-party attacks or vendor risk, supply chain attacks target an organization’s suppliers, vendors, or partners to gain access to their systems and data. These attacks often exploit security vulnerabilities in the supply chain to compromise multiple organizations.

5. Distributed Denial of Service (DDoS) Attacks: DDoS attacks involve overwhelming a target’s network or system with a flood of traffic, rendering it inaccessible to legitimate users. DDoS attacks can cause severe downtime and service disruptions.

6. Advanced Persistent Threats (APTs): APTs are sophisticated, coordinated cyberattacks by well-funded threat actors or nation-state groups that target specific organizations for espionage, data theft, or sabotage. APTs often use advanced techniques and tactics to evade detection and maintain a long-term presence within a target’s network.

7. Zero-Day Exploits: Zero-day exploits are attacks that take advantage of previously unknown security vulnerabilities in software or systems. These vulnerabilities, also known as zero-day flaws, have no existing patches or fixes, making them particularly dangerous and challenging to defend against.

8. Internet of Things (IoT) Security: The increasing adoption of IoT devices and connected technologies has expanded the attack surface for cybercriminals. IoT devices are often vulnerable to cyber threats due to weak security measures, creating new risks for organizations and consumers.

9. Data Breaches: Data breaches occur when unauthorized individuals gain access to an organization’s sensitive data, such as customer information, financial records, or intellectual property. Data breaches can result in significant financial and reputational damage for organizations.

10. Cloud Security Threats: As more organizations migrate to cloud-based services, cloud security has become a critical concern. Threats in the cloud can arise from misconfigurations, weak authentication mechanisms, and vulnerabilities in cloud applications or infrastructure.

Benefits of Open-Source CyberSecurity tools

Open source cyber security monitoring tools offer numerous advantages over proprietary solutions, making them an attractive option for businesses, organizations, and individuals looking to enhance their security posture and perform effective security testing.

Here are some key benefits of using open-source tools for cyber security monitoring for monitoring services that pose security threats, even if you have another network monitoring system. Proper cybersecurity monitoring and access management are key to maintaining a secure environment.


One of the most significant benefits of open-source cyber security tools is their cost-effectiveness. With no licensing fees or subscription costs, these free tools enable security teams to access powerful network monitoring solutions without breaking the bank.

This particularly benefits small businesses and startups with limited budgets, allowing them to allocate resources to other critical areas.

Customizability and Flexibility

Open-source network monitoring tools offer high customizability and flexibility, allowing security professionals to tailor the tools to their specific needs. This adaptability enables organizations to address unique security threats and vulnerabilities, ensuring a more robust security posture.

Additionally, the ability to integrate these tools with existing security infrastructure adds an extra layer of protection to network security.

Rapid Development and Updates

The open-source community is known for its rapid development and frequent updates. As new security threats and vulnerabilities emerge, open-source cyber security tools are often among the first to receive patches and updates.

This continuous monitoring and proactive response help organizations stay ahead of potential security risks and maintain a strong security posture.

Extensive Support and Collaboration

Open-source cyber security tools benefit from an extensive support network, comprising developers, users, and experts from around the world.

This collaborative environment fosters knowledge sharing, allowing security professionals to learn from one another and develop more effective security strategies.

Additionally, the availability of comprehensive documentation and online forums makes it easier for users to troubleshoot issues and enhance their understanding of network monitoring and security.

Improved Security and Transparency

With their source code openly available for inspection, open-source cyber security tools offer greater transparency than proprietary alternatives. This transparency allows security professionals and researchers to scrutinize the code for potential security vulnerabilities and ensure its integrity.

Moreover, the collaborative nature of the open-source community means that any identified issues are addressed quickly, further enhancing the overall security of these tools.

Platform Independence and Interoperability

Open-source network monitoring software often supports a wide range of operating systems, including Windows, macOS, and Linux, allowing organizations to deploy these tools across diverse environments.

This platform independence and interoperability help organizations ensure comprehensive network monitoring, regardless of the underlying infrastructure.

Top 25 Open Source Cyber Security Monitoring Tools in 2023

Note the following free cyber security monitoring tools in 2023 and the open-source list of solutions you can take advantage of and no free trial needed.